Browsing by Author "Pavithra, Jayachandran"

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DYE SENSITIZED SOLAR CELL ACTION OF SN(IV)TETRAKIS(4-PYRIDYL) PORPHYRINS AS A FUNCTION OF AXIAL LIGATION AND PYRIDINE PROTONATION
(Springer Link, 2021-01-03) Pavithra, Jayachandran; Abiram, Angamuthu; Praveena, Gopalan
This contribution reports on the photosensitizing competence of Sn(IV)tetrakis(4-pyridyl)porphyrins (SnTP) for potential applications in dye sensitized solar cell (DSSC). The photosensitization of SnTPs is accounted on the basis of different axial ligands (OH−, Cl−, and H2O) and the pyridine protons. The qualitative information on the photovoltaic performance of the sensitizers is obtained at B3LYP/6-31+G(d) level of theory with LANL2DZ basis set for Sn atom through the calculation of parameters such as free energy change of electron injection (ΔGinject) and regeneration (ΔGreg), oxidation potentials, exciton binding energy, open-circuit voltage, light harvesting efficiency and quantum reactivity descriptors. The evaluation of solvent effects is carried out in Tetrahydrofuran (THF) and Dimethylformamide (DMF) solutions employing conductor-like polarizable continuum model (C-PCM). The overall results emphasize that the enhanced photo-sensing action can be achieved by the Sn complexes having OH− and Cl− ligands without pyridine protonation.
DYE SENSITIZED SOLAR CELL ACTION OF SN(IV)TETRAKIS(4-PYRIDYL) PORPHYRINS AS A FUNCTION OF AXIAL LIGATION AND PYRIDINE PROTONATION
(Springer Link, 2021-01-05) Pavithra, Jayachandran; Abiram, Angamuthu
This contribution reports on the photosensitizing competence of Sn(IV)tetrakis(4-pyridyl)porphyrins (SnTP) for potential applications in dye sensitized solar cell (DSSC). The photosensitization of SnTPs is accounted on the basis of different axial ligands (OH−, Cl−, and H2O) and the pyridine protons. The qualitative information on the photovoltaic performance of the sensitizers is obtained at B3LYP/6-31+G(d) level of theory with LANL2DZ basis set for Sn atom through the calculation of parameters such as free energy change of electron injection ( ) and regeneration ( ), oxidation potentials, exciton binding energy, open-circuit voltage, light harvesting efficiency and quantum reactivity descriptors. The evaluation of solvent effects is carried out in Tetrahydrofuran (THF) and Dimethylformamide (DMF) solutions employing conductor-like polarizable continuum model (C-PCM). The overall results emphasize that the enhanced photo-sensing action can be achieved by the Sn complexes having OH− and Cl− ligands without pyridine protonation.
ELECTROCHEMICAL PERFORMANCE OF SODIATED 1,4-BENZOQUINONE CONFORMERS
(SpringerLink, 2023-02-04) Pavithra, Jayachandran; Abiram, Angamuthu; Praveena, Gopalan
The exploration on the redox properties of sodiated quinone molecules as organic cathode material in sodium-ion batteries has been comprehensively studied. As the electrochemical performance of the cathode material is known to depend on the intrinsic molecular properties such as conformations, the present work focuses on the redox properties of sodiated 1,4-benzoquinone (1,4-BQ) conformers employing the density functional theory. Such investigation on the sodiated structures might provide insight on the discharge state of the puckered conformers. The 38 conformers of 1,4-BQ (2 chairs, 6 boats, 6 skew-boats, 12 half-chairs, 12 envelopes) constructed from the torsion angles given by Berces et al. are optimized at B3LYP/6–311 + G(d,p) level of theory and their structural propensities during the reduction process are explored. The influence of puckering over the charge distribution of neutral, anionic and sodiated structures is analysed using the natural bond orbital method. The electrochemical performance of Na incorporated conformers is explored through the calculation of electron affinity, change in Gibbs free energies and redox potentials. The conductor-like polarizable continuum model (C-PCM) is used to include the solvation effects of the electrolyte such as ethylene carbonate. A good correlation between the conformers with more negative lowest unoccupied molecular orbital (LUMO) energies and their redox potentials and electron affinity is observed. Noticeable variation in the frontier energies and redox potentials of the sodiated quinone conformers emphasize the significance of intrinsic molecular level properties to play a major role in the overall electrochemical performance of quinone-like electrode materials in sodium-ion batteries.
ELECTROCHEMICAL PERFORMANCE OF SODIATED 1,4-BENZOQUINONE CONFORMERS
(Springer Link, 2023-02-04) Pavithra, Jayachandran; Abiram, Angamuthu; Praveena, Gopalan
The exploration on the redox properties of sodiated quinone molecules as organic cathode material in sodium-ion batteries has been comprehensively studied. As the electrochemical performance of the cathode material is known to depend on the intrinsic molecular properties such as conformations, the present work focuses on the redox properties of sodiated 1,4-benzoquinone (1,4-BQ) conformers employing the density functional theory. Such investigation on the sodiated structures might provide insight on the discharge state of the puckered conformers. The 38 conformers of 1,4-BQ (2 chairs, 6 boats, 6 skew-boats, 12 half-chairs, 12 envelopes) constructed from the torsion angles given by Berces et al. are optimized at B3LYP/6–311 + G(d,p) level of theory and their structural propensities during the reduction process are explored. The influence of puckering over the charge distribution of neutral, anionic and sodiated structures is analysed using the natural bond orbital method. The electrochemical performance of Na incorporated conformers is explored through the calculation of electron affinity, change in Gibbs free energies and redox potentials. The conductor-like polarizable continuum model (C-PCM) is used to include the solvation effects of the electrolyte such as ethylene carbonate. A good correlation between the conformers with more negative lowest unoccupied molecular orbital (LUMO) energies and their redox potentials and electron affinity is observed. Noticeable variation in the frontier energies and redox potentials of the sodiated quinone conformers emphasize the significance of intrinsic molecular level properties to play a major role in the overall electrochemical performance of quinone-like electrode materials in sodium-ion batteries.
QUANTUM CHEMICAL STUDY ON THE STRUCTURE AND ENERGETICS OF BINARY IONIC PORPHYRIN COMPLEXES
(Wiley, 2018-02-02) Pavithra, Jayachandran; Abiram, Angamuthu; Praveena, Gopalan
We study the structural and energetic properties of binary ionic porphyrin molecular complexes [H4TPPS4]2−∙∙∙SnTP using quantum chemical techniques. As the axial ligands and the protonation of pyridine sites highly influence the structure and coordination of metal-containing porphyrin, various structures of SnTP in the presence and absence of axial ligands and pyridine protons were considered. The constructed porphyrins were then made to interact face to face, and the formed complexes were optimized at the HF/STO-3G level of theory. The stability and stack-like interaction of the complexes were analyzed through interplanar spacing, planar angle, and edge-to-edge distance. The structural parameters emphasize the importance of axial ligands for the formation of stack-like structures. The complex that contains axial ligands with pyridine protons, namely [H4TPPS4]2−∙∙∙[X'SnXTPH]4+, shows a perfectly stacked layer with a reasonable interplanar distance, which is confirmed from the calculated counterpoise interaction and deformation energies. The energetic parameters were found to correlate well with the obtained geometries. The molecular electrostatic potential (MEP) maps were obtained to infer the presence of nonbonded interaction between the binary ionic porphyrins.
REDOX POTENTIALS OF PUCKERED 1,4-BENZOQUINONE
(Indian Academy of Sciences, 2022-02-10) Pavithra, Jayachandran; Abiram, Angamuthu; Praveena, Gopalan
The present study explores the conformational dependence of the redox potentials of 1,4-benzoquinone (1,4-BQ) molecule employing density functional theory (DFT). The basic 38 conformers of 1,4- BQ (2 chairs, 6 boats, 6 skew-boats, 12 half-chairs, 12 envelopes) were extracted following the IUPAC nomenclature by Berces et al. and were optimized at B3LYP/6-31?G(d), M06-2X/6-31?G(d) and wB97XD/6-31?G(d) levels of theory. The quantitative analysis was made using the spherical polar coordinates (d, h, and /) and structural parameters. The electrochemical performance is explored through the calculation of free energies and redox potentials using conductor-like polarizable continuum model (C-PCM). A good correlation is found between the conformers with more negative lowest unoccupied molecular orbital (LUMO) energies and their redox potentials. The results put emphasis on the variation of redox potential with respect to conformational change of 1,4-BQ molecule and the importance of using B3LYP functional along with the ethylene carbonate solvent for effective electrochemical performance
REDOX POTENTIALS OF PUCKERED 1,4-BENZOQUINONE
(Springer Link, 2022-02-10) Pavithra, Jayachandran; Abiram, Angamuthu; Praveena, Gopalan
The present study explores the conformational dependence of the redox potentials of 1,4-benzoquinone (1,4-BQ) molecule employing density functional theory (DFT). The basic 38 conformers of 1,4-BQ (2 chairs, 6 boats, 6 skew-boats, 12 half-chairs, 12 envelopes) were extracted following the IUPAC nomenclature by Berces et al. and were optimized at B3LYP/6-31+G(d), M06-2X/6-31+G(d) and wB97X-D/6-31+G(d) levels of theory. The quantitative analysis was made using the spherical polar coordinates (d, θ, and ϕ) and structural parameters. The electrochemical performance is explored through the calculation of free energies and redox potentials using conductor-like polarizable continuum model (C-PCM). A good correlation is found between the conformers with more negative lowest unoccupied molecular orbital (LUMO) energies and their redox potentials. The results put emphasis on the variation of redox potential with respect to conformational change of 1,4-BQ molecule and the importance of using B3LYP functional along with the ethylene carbonate solvent for effective electrochemical performance.
SUBSTITUTIONAL EFFECTS ON THE NA-INVOLVED ELECTROCHEMICAL PROPERTIES OF ISOMERIC BENZOQUINONES
(Elsevier, 2023-03) Pavithra, Jayachandran; Abiram, Angamuthu; Praveena, Gopalan
The possibility of the isomeric benzoquinones, 1,2-benzoquinone (1,2-BQ) and 1,4-benzoquinone (1,4-BQ) with electron withdrawing functional groups (-PO3H2, –COOH, –NO2 and –CN), as prospective cathodes in sodium ion batteries is explored applying Density Functional Theory (DFT) approach. In order to investigate the redox behavior of the first and second discharged states, the sodiation of the considered derivatives with one and two number of sodium ions are made. The obtained redox potentials ( of bare quinones are in good agreement with the experimental A linear correlation fit with R2>∼0.95 is found to exist between the obtained LUMO (lowest unoccupied molecular orbital) energies and In general, higher of ∼ 4.2 V with charge capacities of 186mAh/g and 258mAh/g is observed for NO2 and CN containing BQ derivatives. Unexpected deviation in of phosphonate derivatives emphasizes the role of intramolecular hydrogen bonds, conformational changes and steric hindrance on the redox properties.
SUBSTITUTIONAL EFFECTS ON THE NA-INVOLVED ELECTROCHEMICAL PROPERTIES OF ISOMERIC BENZOQUINONES
(Elsevier, 2023-03) Pavithra, Jayachandran; Abiram, Angamuthu; Praveena, Gopalan
The possibility of the isomeric benzoquinones, 1,2-benzoquinone (1,2-BQ) and 1,4-benzoquinone (1,4-BQ) with electron withdrawing functional groups (-PO3H2, –COOH, –NO2 and –CN), as prospective cathodes in sodium ion batteries is explored applying Density Functional Theory (DFT) approach. In order to investigate the redox behavior of the first and second discharged states, the sodiation of the considered derivatives with one and two number of sodium ions are made. The obtained redox potentials ( of bare quinones are in good agreement with the experimental. A linear correlation fit with R2>∼0.95 is found to exist between the obtained LUMO (lowest unoccupied molecular orbital) energies and In general, higher of ∼ 4.2 V with charge capacities of 186mAh/g and 258mAh/g is observed for NO2 and CN containing BQ derivatives. Unexpected deviation in of phosphonate derivatives emphasizes the role of intramolecular hydrogen bonds, conformational changes and steric hindrance on the redox properties.
UV-VIS ABSORPTION SPECTRA OF SN(IV)TETRAKIS(4-PYRIDYL) PORPHYRINS ON THE BASIS OF AXIAL LIGATION AND PYRIDINE PROTONATION
(Springer Link, 2019-09) Pavithra, Jayachandran; Abiram, Angamuthu; Praveena, Gopalan
The present study highlights the structural and electronic spectra of Sn(IV)tetrakis(4-pyridyl) porphyrins (SnTP) using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The impact of axial ligands (OH-, Cl-, and H2O) and protonation at pyridine sites on the excitation properties of SnTP is also explored. The considered SnTPs were optimized at B3LYP/6-31+G* level of theory with LANL2DZ basis set for Sn metal. The effects of tetrahydrofuran (THF) and dimethylformamide (DMF) solvents were also assessed employing conductor-like polarizable continuum (C-PCM) model. The observed structural effects correlate well with the experimental data and clearly depict the impact of axial ligands on the SnTP ring. The absorption spectra along with the frontier orbitals in all three phases show noticeable dependence of axial ligation on the photophysical properties of SnTPs. The transition character of molecular orbitals and their respective density of states (DOS) were explored to infer the orbitals involved in electronic transitions. Graphical abstract The structural and electronic spectra of Sn(IV)tetrakis(4-pyridyl) porphyrins (SnTP) were examined using time-dependent density functional theory (TDDFT). Axial ligation and pyridine protonation significantly affects the absorption properties of Sn complexes. The overall results suggest the application of [(OH-)Sn (OH-)TP] and [(Cl-)Sn (Cl-)TP] as photosensitizers.
UV-VIS ABSORPTION SPECTRA OF SN(IV)TETRAKIS(4-PYRIDYL) PORPHYRINS ON THE BASIS OF AXIAL LIGATION AND PYRIDINE PROTONATION
(Springer Link, 2019-09-02) Pavithra, Jayachandran; Abiram, Angamuthu; Praveena, Gopalan
The present study highlights the structural and electronic spectra of Sn(IV)tetrakis(4-pyridyl) porphyrins (SnTP) using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The impact of axial ligands (OH−, Cl−, and H2O) and protonation at pyridine sites on the excitation properties of SnTP is also explored. The considered SnTPs were optimized at B3LYP/6-31+G* level of theory with LANL2DZ basis set for Sn metal. The effects of tetrahydrofuran (THF) and dimethylformamide (DMF) solvents were also assessed employing conductor-like polarizable continuum (C-PCM) model. The observed structural effects correlate well with the experimental data and clearly depict the impact of axial ligands on the SnTP ring. The absorption spectra along with the frontier orbitals in all three phases show noticeable dependence of axial ligation on the photophysical properties of SnTPs. The transition character of molecular orbitals and their respective density of states (DOS) were explored to infer the orbitals involved in electronic transitions.